CCM cluster - mixed hardware models

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Feb 19th, 2009
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sorry if it might has been asked before but i have this case:

i have a TWO 7835 MCS servers and ONE 7816 MCS server CCM version is 6.1

I want to use 7816 server as publisher and i want to configure this publisher as datbase server only I WILL NOT activate callmanager service and WILL NOT activate tftp service on it (it's role only to maintain the database)

I'll add the other 7835 servers will be subscribers and tftp servers

my question is will cluster in this design work, can 7816 publisher in this case work without any performance issues?

Thanks in advance

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Overall Rating: 5 (5 ratings)
bigcappa1 Thu, 02/19/2009 - 06:03
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What you want to do will not work.

First thing the 7816 is a less powerful box than the 7835, as the publisher is the workhorse it should be on the most powerfull box you have.

Second you cannot run the Publisher without running the CCM service, so if you dont activate it you dont have a publisher and the subscribers wont synch.

The TFTP service can run on other servers but again even if a server is not used as a publsher and just a TFTP server it still needs the ccm service to be part of the cluster.

So recommend you use one of the 7835 servers as the publisher another as the publisher and the 7816 as the backup

Hope this helps


Chris Deren Thu, 02/19/2009 - 06:04
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Publisher actaully requires more horsepower, so I would not do it this way. If you monitor the systems you will see that cpu and memory utilization is always higher on Pub, if anything I would use the 7916 as my backup sub.



user-cisco Thu, 02/19/2009 - 06:11
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thanks guys for your replies, actually i missed to mention that i'll have around 2000 users

in my case Publisher I'll not include the publisher in callmanager group list of my phones so it will not participate in call processing functionalitiy

the ip phones are only registered to the 7835 servers

so can I use 7825 server as a publisher in my case considering my notes above and in my previous posts as 7825 is more powerful than 7816


Chris Deren Thu, 02/19/2009 - 06:19
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My recommendation stands, use the most powerful server for Pub. Pub is always involved in call processing, it's not just DB master, if your publisher's utilization goes up you will notice call setup delay etc, that's because the endpoints use the CMs' DB first to determine call routing, etc, only if it's unavailable they use sub replica.



Rob Huffman Thu, 02/19/2009 - 06:22
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Hi UC,

Just to add a note to the great tips from Chris and Paul (+5 points each guys for your good work:)

You will need to be careful with this design as far as failover goes. The 7816 only supports 300-500 users depending on what doc you read. You will want to keep this in mind when designing your Callmanager Groups;

Here are the base numbers the SRND;

Maximum Number of Devices per Server Platform

Cisco MCS 7845 (All supported models)


Cisco MCS 7835 (All supported models)


Cisco MCS 7825 (All supported models)


Cisco MCS 7815 or MCS 7816 (All supported models)


From this excellent section of the 6.x SRND;

Unified CM Platform Capacity Planning')">

Hope this helps!



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